Dredge construction



United States Patent DREDGE CONSTRUCTION L John H. Forkner, Rte. 13, Box531, Fresno, Calif.

" Filed July 27, 1956, Ser. No. 600,449

4 Claims. ((11. 37-71 1 This invention relates generally to dredges ofthe type generally carried by pontoons or barges and adapted to operateon underwater formations. In particular the invention is applicablewhere it is desired to recover mineral values contained in theformation.

In the past dredges of the endless bucket line type have been used toremove underwater formations for treatment to recover gold or othermineral values. Such equipment isrelatively costly and its use isprohibitive except in relatively few locations where warranted by provenmineral values. The high cost is due largely to the extensive bucketline and its supporting ladder, and the relatively large barge requiredto float the working parts. In the operation of such dredges, as in theoperation of barge mounted scoops or shovels, the buckets containing theremoved material are lifted out of the water, and this characteristicmust be taken into account in designing the size of barge employed, andthe power requirements. Efforts have been made to use dredges of thesuction type in gold dredging and like operations. Such dredges have thetheoretical advantage that the underwater operating parts need not belifted above the water level for discharge of the dredged solids, andtherefore the size of the barge or pontoons employed may be reducedaccordingly. In addition the over-all construction of such suctiondredges is relatively simple compared to the dredgw of the bucket linetype. However the performance of suction dredges as heretoforeconstructed have been disappointing, particularly since the proven assayvalue of the formation being'dredged has not been realized in theprocessed material. It has been found that this is due to a loss ofvalues occurring in the region generally adjacent to the suction head,which probably results from a dropping out of the heavier gold ormineral values from the mineral moving toward the suction head.

In general it is an object of the present invention to provide animproved dredge construction and method which will make use of hydraulicsuction, but which will avoid the defects and difficulties outlinedabove.

Another object of the invention is to provide a dredge construction andmethod of the above character which will be relatively inexpensivecompared to dredges of the bucket line type, and which therefore can beused in many instances where more elaborate equipment would beprohibitive.

Another object of the invention is to provide equipment of such acharacter that it may be land borne for test or exploratory operations.

Another object of the inventionis to provide a dredge construction andmethod of the suction type in which a classifying action takes place inconjunction with movement of material to the suction head.

Another object of the invention is to provide an equipment and methodcapable of coping with flash flood conlarge rocks found in the formationare placed back into previously worked areas without lifting the samefrom the water.

Another object of the invention is to provide a suction dredge in whicha classifying action takes place without clogging of the suction head.

A further object of the invention is to provide a we tion dredge andmethod in which the pumping means is mounted in such a manner withrespect to the suction head, as to produce a relatively powerful suctionwith a minimum amount of power consumption.

lAdditional objects and features of the invention will appear from thefollowing description in which the preferred embodiment of the inventionhas been set forth in detail in conjunction mm the accompanying drawing.

Referring to the drawing:

Figure 1 schematically illustrates dredging apparatus incorporating thepresent invention.

Figure 2 is an enlarged detail in section illustrating the bucket andsuction head.

Figure 3 is a cross-sectional view taken along the line 3--3 of Figures1 and 2.

i In accordance with the present invention digging means of the bucketor dipper type is employed for operating upon a bank or other underwaterformation. A special suction head is disposed directly within the bucketand is connected to pumping means for creating the requisite hydraulicsuction. When in operation material within the bucketis classified as tosize with the smaller sized material carrying the desired mineral valuespassing into the head and being discharged upon the barge, and therelatively large boulders and rock remaining in the bucket. Accumulatedboulders or rock are from time to time discharged in previously workedunderwater areas where they will not interfere with continuedoperations.

Referring to the particular construction illustrated in the drawing, Ihave shown a dipper or bucket 10 having a bottom 11 provided with adigging edge or teeth 12. The front side of the bucket, above thedigging edge is open to receive material. The bucket is shown carried bythe rigid structural member 13 which is generally referred to as abucket stick. As representative of suitable means for carrying the stick13, and for operating the same as required for the various digging anddischarge operations, I have shown a boom 14 to which the stick isattached by a pivot pin 16. The boom in turn is carried by the pontoonsor barge parts 17, and by means of operating cables 18, it can be raisedor lowered as desired. Additional operating cables 19 and 21 can bemanipulated as by winches located on the pontoons, and serve to swingthe stick for digging and return movements of the bucket.

The stick 13 also serves to mount the centrifugal pump 22, which has itsdischarge connected to a conduit 23 that extends above the water levelfor discharging material for processing. The driving means illustratedfor pump 22 includes the electric motor 24 and gear box 26, whichpreferably are likewise mounted upon the stick. Conduit 27 connects withthe inlet side of pump 22, and at its lower end is connected by journalcoupling 28 with the hollow suction head 29. The suction head preferablyconsists of a Wall which may be cylindrical, and which is provided witha plurality of perforations 31. It is desirable for the lower end of thehead to be journaled .to the lower wall of the bucket as indicatedschematically at 32. A shaft 33 extends downwardly through conduit 27from pump 22, and has a driving connection with the head. This shaftrotates with operation of the pump, and serves to cause cont-inuousrotation of the' head. As will be presently explained a perforated headof this type makes it possible to carry out size classification withinthe bucket, and at the same time continuous motion of the head preventsclogging of the perforations 31.

scribed above the head rotates continuously, it will be evidentthatitrnay be oscillated or reciprocated with sufficient amplitude to,prevent clogging of'the 'per fora t-ions If desired the head maybeprovided withribs or corrugation that may extend inan axialdirection',to aid in breaking conglomerate material beingpressed against terialtends Pressed against sthe'headby the Con sm 'n action of the bucket",during digging operations.

The head29 extends substantially the entire height of the space 36within the bucket andris locatedsbetween' the open front of the bucketand the bucket back-wall; and between the side walls.

It 'islndesirable to provide theflbucket with hydraulicjettingnozzles!Thusoneiorh'lore nozzlesslfl "connect with the watersupplyfpipe 38,wandsare ,di'sposed tofdischarge/ in a direction rearwardly immtheopen,irontjof Although as de- T 4 thesame. In" this connectionit maybenotedthat'mal ing action with a minimum amount of power. m.My,-dredge isparticularly applicable for use in the tropics or like regions whereminimum servicing is dB-' sir ahle, and where i the equipment mustwithstand adverselw'eather, conditions, such as floods. In the eventofflash flood conditions, the stick can be lowered'nnfil the bucketrestsqupon the bottom. The "pin 16can be re moved to allow the stick to(drop to the bottom, with only ja cable serving toattach it to thebarge. This serves to relieve thebargeof-the' weight of :aconsiderableipartu t "of theoperating equipment, Asfurther rneasuresytheu q boom-l tycan-be disconnected and dropped totthe bottom,u-; s

the buckehyand toward the head29; As} will presently be explained'suehijets tend AEO breakup material mov ing intolthe bucket duringdigging operations and aid in the desired classifying action Also theyaid in creating a how into the suction head. Additional jetting 5nozzles 39 communicate through the rear jwall of the bucketand connectwith the water supply pipe'411fi Jets discharging from nozzles 39 eanbeemployed maid in removing rocks, boulderspandthe like iromithe' bucket;Suitable means (not shown) such'as Valvesnareemployed to selectivelycontrol operation ofithese nozzles, whereby one or the other (ie, 37M39)" is operatedat one,

only, time. i

,7 Operation of the dredge described above as follows: i a

In Figure i it is assumed, that an underwater bank 42 containsgold orother values and is to be operatedflupons by the bucket. ly maintainsuction tending tohydraulically move mate'- 7 rial into the; suctionhead 29 'The operatormanipulate's the bucket whereby it is swung intothe bank 42 along I an rare as illustrated, whereby material is "forced.into the bucket. Within the bucket the smallersized material capable ofpassing'through the perforations 31; is hy- Thepump 22 is operated tocontinuous-i draulieally conveyed intothe head throughwthese peters i Itions. Hydraulic movement-into the headis'faeilitated' confined, region36 of the bucket there is no opportunity uby the action of the hydraulicjets 37, and in addition v 'thesejets act'upon masses ofaggregatestobreakthernu 5;

up, thus freeing the smallersized materiaL Within the i t i for gold orlike heavy minerals to separateout without being hydraulically movedinto the head, Assuming that the formation contains some largerocksorboulders, whieh do notcontain values, these remain within the bucketand after one or'more sweeps against theforma-J tion, the bucket may beswung to airearpo'sition such as illustrated indebted lines," wherebyrocks are dis charged in an area not being operated upon; such as anarea that has'previously been worked; As illustrated by the dotted lineposition of the bucketpafter swinging the :buoket'to its real-mostposition for discharge of the g 1 :rocksyor boulders, it may beliflted'somewhat from the 7 7 formation for its return swing toclearythedeposited rocks. The discharge of the rocks or boulders can beiai-ded by jetting water from'the nozzles It will be 'evidentflirom theforegoing thatlhave pro the jets, 37. 'Allof the gold or other mineralvalues head and delivered to the top of the-barge, 'and does not have anopportunity to settle out or otherwise he J come lost, The mineralbearing material is delivered 'to the top of the barge, and ll i l llfilil d boulders and I h h the enclosed space within the bucket. videdan apparatus and method having a number of f desirable features. Withrespect tothe methodem-- ployed, classification and hydraidic removal ofthe smaller I sized material iromfthe interior of the bucket takes placeconcomitantly with digging operations, and this likewise applies tobreaking up the formation by the; action for generator, and retract theboom, stick and bucket. n

' fWhilemy eq uiprnentis intended primarily for installa I tiononbargesor pontons, it may be made; land borne,

in which ,event it is supported by a carrier oi the track I I1ayingor1rubbertired wheel type. For exaniple the ,carriermay'heatracklaying or tiredtracton'in which; I i event" the tractor can bemanipulated during diggingandj load discharge-operations, wherebythebucket digs inthe q manner of a. back-hoe. 7 Washing orother hydraulic Yequipment for, recovering the desired values can be 10 catedonthentraetor, or on a separate trailerr When, i carried in this unannerthe equipment can be used to: 1

advantage for test or exploratory purposes;

Injdescribingthe apparatus as illustrated inthe draw i 1-ing,;it isassumed that the bucket is movedforwardlyyagainst theaformationhHowever, the bucket can be-op eratedin; the mannerof' a hoe, and insuch. event'when Q operating "upon abank, the bucket is engaged withqtheH upper portionof the bank and thenswung' downwardly: V with diggingaction to move the material into the bucket, r

Itclairn': I

;1.: In aqdredge 'eonstructiom a bucket having digging; 1 means on alower wall, a stick serving to mountthe; bucket; a carrier; pivotedmeans onthe carrier for sup, porting the stick, a pump mounted upon thestick, means j m'ounted on thestick for driving thepurnp, a suction;head disposed within the space enclosed by the bucket, {said headcomprising a vertically extending hollow mem her having perforations ofa size suitable-for passing. desired material, said head beingjournalled for turning, 2 within said bucket, means for cyclicallyturning the head to ,prevent'cloggingo i the perforations withdredgedmaterial, nozzle; means for delivering water jets into, the

bucket andf inthe direction towardsthe suction head fromthe open frontofthe-fbucket, andsadditional nozzle means carried, by the bucket anddisposed to delivery jets of water into the bucket andtowar'd thexopenfront -ilthereof todischargeover-sized material. I a

4 2. Thedredgeof claim I wherein said head and said perforations .extendforsubstantially the entire-height of 3 In a dredge construction, asubstantially enclosed bucket having digging means one lower wall,support,v nieansserving 'to mount'the hucket'for digging operations,suction means includingla suction conduitextending to the bucket, asuction head mountedwithinthe enfcl'os cd space of said bucket formovementsrelative'to V the bucket and to dredgedrmaterialcontained'therein, [said suction headbeing in fluid communication withthe suctionco nduit, said suction head being also provided with aplurality of inlet openings dimensioned to limit V and :elassifythe sizeof material passinginto' said 'suc-' V I tipn head and conduit, andmeans for cyclically moving said suction head to prevent clogging ofsaid inlet openings.

4. In a dredge construction, a substantially enclosed bucket havingdigging means on a lower wall, support means serving to mount the bucketfor digging operations, suction means including a suction conduitextending to the bucket, a suction head mounted within the enclosedspace of said bucket and movable relative thereto, said suction headbeing in fluid communication with the suction conduit, said suction headbeing provided with a plurality of inlet openings, means for applyingcyclic movement to said suction head to prevent clogging of said inletopenings, and nozzle means within the bucket for discharging jets ofwater towards the suction head and in the direction toward the openfront of the bucket, said nozzle means serving to cause smaller par- 6ticles to enter the suction head and larger oversized ma.- terial to bedischarged from the bucket.

References Cited in the file of this patent UNITED STATES PATENTS

